Device for rapid closure and pressurization of a compression chamber

ABSTRACT

The rapid closure device for the pressurization of vessels used primarily for isostatic pressing of sintered powders comprises a removable jack-operated spherical plug valve fitted within a cylindrical shell between a double-acting piston slidably mounted in an adjustable seal plug and a valve-seat lining placed in the trued base of the shell. The plug valve is rotated and maintained in the closed position by means of a fluid under pressure which is also directed towards an adjustable pressure multiplier comprising a two-stage ram slidably mounted within a low-pressure cylinder and a highpressure cylinder.

United States Patet David et a1.

[111 3,869,241 [451 Mar. 4, 1975 DEVICE FOR RAPID CLOSURE AND PRESSURIZATION OF A COMPRESSION CHAMBER Inventors: Jacques David; Guy Gay, both of Orange, France Assignee: Commissariat A LEnergie Atomique, Paris, France Filed: Jan. 7, 1974 Appl. No.: 431,510

Foreign Application Priority Data Jan. 11, 1973 France 73.00887 U.S. Cl. 425/405 H, 425/450 Int. Cl. B3011 5/02, B301) 11/00 Field of Search 425/405 H, 450 R References Cited UNITED STATES PATENTS 10/1971 Landa et al 425/405 H X ll/l97l Rietmann 425/405 H X Baxendale et a1. 425/405 H X FOREIGN PATENTS OR APPLICATIONS 11/1970 Germany Primary E.raminer-J. Howard Flint, Jr. Attorney, Agent, or FirmLane, Aitken, Dunner &

Ziems ABSTRACT The plug valve is rotated and maintained in the closed position by means of a fluid under pressure which is also directed towards an adjustable pressure multiplier comprising a two-stage ram slidably mounted within a low-pressure cylinder and a high-pressure cylinder.

11 Claims, 1 Drawing Figure DEVICE FOR RAPID CLOSURE AND PRESSURIZATION OF A COMPRESSION CHAMBER This invention relates to devices for the rapid closure of chambers under pressure and to vessels in which devices of this type are employed, especially for isostatic pressing of sintered powders which are encountered in such applications as the fabrication of ceramic bodies of automobile spark plugs or for the requirements of chemistry of reactions under pressure.

Devices for closing a compression chamber are already known which comprise closure means mounted on a first extremity of the compression chamber, a pressure multiplier in communication with the second extremity of said chamber and means for application of pressure for the closure means and the pressure multiplier.

One aim of the present invention is to provide a closure device which is much more rapid than the known devices and to apply it to a compression chamber. A further aim of the invention is to provide a closure de vice which can be adapted to an automatic machine of industrial type and in which the pressure application means can be controlled.

To this end, the invention proposes a closure device which is characterized in that it comprises:

rapid closure means comprising an obturator with a removable jack interposed between the two arms of a goose-neck frame which is rigidly fixed to the compression chamber,

a valve-seat lining applied against the first extremity of said chamber by a jack which is subjected to the action of means for application of pressure,

an axial aperture formed in the base of the second extremity. of said chamber and adapted to communicate with the pressure multiplier which is actuated by the pressure-application means.

By virtue of this very important feature, the jack can be removed from between the arms of the gooseneck frame, with the result that maintenance of the jack is facilitated and that, during operation, leak-tightness between said jack and the compression chamber is ensured by the means employed for applying pressure to the jack.

In accordance with one particularly advantageous embodiment of the invention, the jack comprises a cylindrical shell with a trued bottom end-face in communication with the compression chamber and an adjustable seal plug at the end remote from said end-face in communication with a passage at atmospheric pressure which is formed in the adjacent arm of the gooseneck frame. A rotatable spherical plug-valve is fitted within the cylindrical shell between a double-acting piston which also slides within the adjustable seal plug and the valve-seat lining which is placed in the trued end-face. The plug valve is operated by means of a leak tight stem which passes through the cylinder wall and to which access can be gained from the exterior.

Tightening of the seal-plug makes it possible to obtain pre-sealing of the components of the jack-operated obturator which is applied against the compression chamber. This preliminary setting of the jack does not produce action on the spherical plug-valve and this latter retains free rotational motion on its valve-seat lining as long as the fluid under pressure is not applied to the piston. This accordingly prevents any damage to said lining. i

In accordance with one advantageous and characteristic feature of the invention, the adjustable seal plug and one face of the piston determine a jackJocking chamber in direct communication with a fluid supply line in such a manner as to apply the spherical plug (in the closed position) against the valve-seat lining, with the result that the compression chamber is thus hermetically closed.

In accordance with another characteristic feature, the bottom end-face of the cylindrical shell and another face of the double-acting piston determine a releasing chamber in direct communication with another supply line for fluid under pressure. The admission of fluid into the releasing chamber has the effect of lifting the spherical plug and moving this latter away from its seatlining in order to return said plug to the open position which connects the compression chamber to atmospheric pressure at the end of the operation.

In another embodiment of the invention, the pressure multiplier is removable and comprises two cylinders in tandem, namely a'high-pressure cylinder which is in communication with the compression chamber and a low-pressure cylinder which is in communication with the pressure-application means, a ram having two stages each corresponding respectively to the diameters of said cylinders. Said pressure multiplier comprises an adjustable end-plug which serves to close the low-pressure chamber and ensures presealing of said chamber. The ratio between the diameters of the cylinders makes it possible to multiply the initial pressure which is applied to the low-pressure ram.

The pressure-application means comprise supply lines for fluid under pressure with a manostat which is interposed in thesupply line of the low-pressure cylinder. A manostat maintains the pressure at a reference value within the low-pressure cylinder.

There is shown diagrammatically in the single accompanying figure one embodiment of the invention which is given by way of example and not in any limiting sense.

In the figure, the reference numeral 1 designates a compression chamber in which is placed a body to be processed under pressure (not shown). A jackoperated obturator 2 and a pressure multiplier 3 are mounted on the respective extremities 5 and 6 of the chamber I. Said chamber has walls 4 of sufficient thickness to withstand operating pressures and to ensure safety; its extremities 5 and 6 are machines so as to fit perfectly in relation to the jack-operated obturator 2 and the pressure multiplier 3.

The removable assembly formed by the jack-operated obturator 2 is interposed between the two arms 7a, 7b of a gooseneck frame 8 which is rigidly fixed to the chamber 1. Leak-tightness between the jack-operated obturator 2 and the chamber 1 is ensured by the components which form part of the jack as will be described hereinafter and by a fluid under pressure which is applied to said components.

The jack proper comprises a cylindrical shell 9 within which are disposed in sequence: a valve-seat lining 10 having the shape of a hemispherical cup, a spherical and rotatable plug 11, a seal 12, a double-acting piston 13 which is also slidably mounted within a seal plug 14 provided with a nut 15. Leak-tightness between the different components is ensured by means of packingrings such as the ring 16 in the case of the piston 13, the ring 16a in the case of its guide-bush 13a, the ring 14a in the case of the seal plug 14. The seal- 12 ensures internal leak-tightness between the valve plug 11 and the piston 13.

The rotation of the spherical plug 11 is controlled by an operating-stem 18 which passes in leak-tight manner through the wall of the shell 9 and is actuated from the exterior, either by hand or by a control knob 19 or any other means, or by means of a servo-controlled device which does not form part of the invention.

The seal plug 14, the double-acting piston 13, the spherical plug valve 11 and the valve-seal lining as well as the trued bottom end-face 45 of the shell 9 are provided with axial passages numbered respectively and in sequence from 20 to 23. A passage 24 of identical cross-sectional area which is formed in the arm 7b of the gooseneck frame 8 corresponds to the passage 20 of the seal plug 14. In the open position (as shown in the figure) of the spherical plug valve 11, the compression chamber 1 communicates with the exterior (atmospheric pressure) without any break in continuity.

Within the obturator 2, the seal plug 14 and a top face 13b of the piston 13 determine a jack-locking chamber 25 whilst the base of the shell 9 and the bottom face 13c of the piston 13 determine a releasing chamber 26. The locking chamber 25 communicates with a supply line 28 for fluid under pressure through ducts 29, 30 formed in one case in the arm 7b and in the other case in the seal plug 14. Said ducts are placed in coincident relation as the result of the actual assembly of the obturator 2. The releasing chamber 25 communicates with another supply line 29 for fluid under pressure through ducts 31, 32 formed in one case in the base of the shell 9 and in the other case in the first extremity 5. Said ducts 31, 32 are placed in coincident relation in the same manner as the previous ducts by virtue of the assembly of the obturator 2 and by locating means known per se (not shown in the figure).

The pressure multiplier 3 which is mounted on the second extremity 6 of the compression chamber 1 comprises two cylinders in tandem, namely a high-pressure cylinder 36 and a low-pressure cylinder within which is displaceable a ram having stages 37 with respective diameters corresponding to the cylinders.

in the example of construction shown in the figure, the high-pressure cylinder 36 is incorporated in the extremity 6 of the chamber 1 and communicates with this latter through an aperture 50. The low-pressure cylinder 35 is removable and interposed between the endplates 38, 38a of a barrel 39 which is fixed on the second extremity 6.

The low-pressure cylinder 35 communicates through ducts 40 and 41 with a supply line 28a for fluid under pressure, said supply line being fitted with a set-point manostat 42, the intended function of which will be explained hereinafter.

The supply lines 28 and 280 are connected in common to a general line 43 for the supply of fluid under pressure. The supply line 29 is connected separately (although not shown in the figure) to the general supply line 43. The cylinder 35 is closed at its bottom end by a screwed end-plug 47 fitted with a nut 48.

The source of fluid inder pressure and the means for controlling the supply line have not been illustrated since these latter do not form part of the invention.

Before describing the operation ofthe closure device in accordance with the invention, it will be noted that, for maintenance purposes, the jack-operated obturator 2 is interchangeable by virtue of its removable assembly between the arms 70, 7b of the gooseneck frame 8. Moreover, pre-sealing of the closure device on the compression chamber 1 is carried out as a result of application of the seal plug 14 against the arm 71) by means of the nut 15 which is mounted on an external screw-thread of said seal plug. As a result of reaction, the trued end-face 45 is powerfully applied against the face 46 of the first extremity 5. At this precise moment, the ducts 29, 30 and 31, 32 are respectively placed opposite to each other without any break in continuity and pre-sealing of the obturator 2 on the compression chamber 1 is ensured. It will be noted in addition that, under these conditions of pre-sealing, the spherical plug valve 11 is free between the piston 13 and the valve-seat lining 10, with the result that said lining is not liable to incur damage as a result of rotation of the valve-plug 11. Similarly, pre-sealing is ensured within the pressure multiplier 3 by application of the end-face 47 against the end-plate 38a of the barrel 39 by means of the nut 48.

The cycle of operation of the closure device hereinabove described is as follows:

the work-piece or body to be processed (not shown in the figure) is introduced into the compression chamber 1,

the spherical plug valve 11 is pivoted to the position which is closed to atmospheric pressure,

the pressure P of the supply line 28 is applied to the locking chamber 25 via the ducts 29 and 30. The pressure P acts on the piston 13 which exerts a clamping force on the spherical plug 11 and consequently on the valve-seat lining 10,

since the spherical plug 11 is clamped against the lining 10, the flow rate P becomes zero and P, increases to a value corresponding to the set point of the manostat 42, which opens an internal valve (not shown) so as to direct the flow of fluid at the pressure P, through the supply line 28a towards the multiplier 3,

the pressure P, is applied to the ram 37a of the lowpressure cylinder 35. As a result of the ratio of diameters existing between the two cylinders 35 and 36, the high-pressure ram 37b multiplies the pressure from P to a pressure which is higher than P within the compression chamber 1.

At this stage of compression, the chamber 1 remains leak-tight by virtue of the fact that the clamping force F on the lining 10 remains higher than F,, namely the lifting force exerted by P on the spherical plug 11. In fact, the product (F) of the pressure P, and of the surface area (S) of the piston 13 is calculated so as to remain higher than the product (F,) of the pressure P and of the lifting surface area (S passage in the lining 10) on the spherical plug 11, with the result that the ratio between the clamping and lifting forces remains in the proportion: F F,.

When the pressure P, reaches its reference value, a manometric signal applied to the manostat 42 stops the flow of fluid within the supply line 280, with the result that the pressure P;, is maintained for the required period of time.

At the end of the time of application of the pressure P;,, the general supply line 43 is opened to exhaust by means of a valve (not shown) which causes the pressure P, and concurrently the pressureP to drop progressively to zero. At the same time, the volume of fluid contained within the compression chamber 1 expands and returns the ram 37 of the multiplier 3 to its starting point.

When the pressure P, is zero, the clamping force F is not completely cancelled by reason of the molecular adhesion between the spherical plug 11 and the lining 10. In order to cancel this residual force, a flow of fluid at a pressure P is admitted into the releasing chamber 26 through the duct 29 and the ducts 31, 32 so as to lift the piston 13 and to relieve the lining of any stress.

At this moment, the spherical plug 11 can be pivoted to its open position (as shown in the figure) by means of the operating stem 18 and the volume of the compression chamber 1 is restored to atmospheric pressure. The extraction of the body contained in the chamber completes the operating cycle of the device according to the invention.

We claim:

1. A device for the rapid closure and pressurization of a compression chamber comprising closure means mounted on a first extremity of the compression chamber, a pressure multiplier in communication with the second extremity of said chamber, pressure application means for the closure means and the pressure multiplier, wherein said closure device comprises:

rapid closure means comprising an obturator with a removable jack disposed in a frame which is rigidly fixed to the compression chamber,

a valve-seat lining applied against the first extremity of said chamber by said jack which is subjected to the action of means for application of pressure,

an aperture formed in the base of the second extremity of said chamber and adapted to communicate with tthe pressure multiplier which is actuated by the pressure-application means.

2. A device according to claim 1, wherein the jack comprises a cylindrical shell with a trued bottom endface in communication with the compression chamber and an adjustable seal plug at the end remote from said end-face in communication with a passage at atmospheric pressure which is formed in the adjacent arm of the frame. 1

3. A device according to claim 2, wherein the jackoperated obturator comprises a rotatable spherical plug-valve fitted within the cylindrical shell between a double-acting piston which also slides within the adjustlining placed in the able seal valve and one face of said piston determine a jack-locking chamber in direct communication with a fluid supply line in such a manner as to apply the spherical plug against the valve-seat lining.

6. A device according to claim 5 wherein the bottom inner end-face of the cylindrical shell and another face of said double-acting piston determine a releasing chamber in direct communication with another supply line for fluid under pressure so as to detach the spherical valve from the valve-seat lining.

7. A device according to claim 1, wherein the pressure multiplier is removable and comprises two cylinders in tandem, namely a high-pressure cylinder which is in communication with the compression chamber and a low-pressure cylinder which is in communication with the pressureapplication means, a ram having two stages each corresponding respectively to the diameters of said cylinders.

8. A device according to claim 7, wherein the pressure multiplier comprises an adjustable end-plug which serves to close the low-pressure chamber and ensures presealing of said chamber.

9. A device according to claim 8, wherein the pres sure-application means comprise supply lines for fluid under pressure with interposition of a manostat in the supply line of the low-pressure cylinder.

10. A device according to claim 9, wherein the manostat maintains the fluid pressure at a reference value within the low-pressure cylinder.

11. A device for rapidly sealing and pressurizing a vessel comprising:

a compression chamber having fluid inlet and outlet ends; an obturator assembly including a frame rigidly fixed to the outlet end of said compression chamber, a removable fluid pressure operated jack disposed in said frame, said jack having a. cylindrical shell with an apertured end-face, means for urging said endface into sealed communication with the outlet end of said compression chamber, a double-acting pis' ton slidably received within said cylindrical shell, a

valve-seat lining formed in the inner end of said shell about the aperture therein, a rotatable spherical plug-valve fitted within said shell between said piston and said valve-seat lining, a passage to atmospheric pressure being defined through said spherical plug-valve in one orientation, said piston and said frame; and

a pressurizing assembly including a frame rigidly fixed to the inlet end of said compression chamber, and a pressure multiplier operated by fluid pressure disposed in said frame in sealed communication with the compression chamber inlet for pressuriz- 

1. A device for the rapid closure and pressurization of a compression chamber cOmprising closure means mounted on a first extremity of the compression chamber, a pressure multiplier in communication with the second extremity of said chamber, pressure application means for the closure means and the pressure multiplier, wherein said closure device comprises: rapid closure means comprising an obturator with a removable jack disposed in a frame which is rigidly fixed to the compression chamber, a valve-seat lining applied against the first extremity of said chamber by said jack which is subjected to the action of means for application of pressure, an aperture formed in the base of the second extremity of said chamber and adapted to communicate with tthe pressure multiplier which is actuated by the pressure-application means.
 2. A device according to claim 1, wherein the jack comprises a cylindrical shell with a trued bottom end-face in communication with the compression chamber and an adjustable seal plug at the end remote from said end-face in communication with a passage at atmospheric pressure which is formed in the adjacent arm of the frame.
 3. A device according to claim 2, wherein the jack-operated obturator comprises a rotatable spherical plug-valve fitted within the cylindrical shell between a double-acting piston which also slides within the adjustable seal plug and the valve-seat lining placed in the trued end-face.
 4. A device according to claim 3, wherein the spherical plug valve is operated by means of a leak-tight stem which passes through the cylinder wall and to which access can be gained from the exterior.
 5. A device according to claim 3 wherein the adjustable seal valve and one face of said piston determine a jack-locking chamber in direct communication with a fluid supply line in such a manner as to apply the spherical plug against the valve-seat lining.
 6. A device according to claim 5 wherein the bottom inner end-face of the cylindrical shell and another face of said double-acting piston determine a releasing chamber in direct communication with another supply line for fluid under pressure so as to detach the spherical valve from the valve-seat lining.
 7. A device according to claim 1, wherein the pressure multiplier is removable and comprises two cylinders in tandem, namely a high-pressure cylinder which is in communication with the compression chamber and a low-pressure cylinder which is in communication with the pressure-application means, a ram having two stages each corresponding respectively to the diameters of said cylinders.
 8. A device according to claim 7, wherein the pressure multiplier comprises an adjustable end-plug which serves to close the low-pressure chamber and ensures presealing of said chamber.
 9. A device according to claim 8, wherein the pressure-application means comprise supply lines for fluid under pressure with interposition of a manostat in the supply line of the low-pressure cylinder.
 10. A device according to claim 9, wherein the manostat maintains the fluid pressure at a reference value within the low-pressure cylinder.
 11. A device for rapidly sealing and pressurizing a vessel comprising: a compression chamber having fluid inlet and outlet ends; an obturator assembly including a frame rigidly fixed to the outlet end of said compression chamber, a removable fluid pressure operated jack disposed in said frame, said jack having a cylindrical shell with an apertured end-face, means for urging said end-face into sealed communication with the outlet end of said compression chamber, a double-acting piston slidably received within said cylindrical shell, a valve-seat lining formed in the inner end of said shell about the aperture therein, a rotatable spherical plug-valve fitted within said shell between said piston and said valve-seat lining, a passage to atmospheric pressure being defined through said spherical plug-valve in one orientation, said piston and said frame; and a pressurizing assembly including a frame rigidly fixed to the inlet end of said compression chamber, and a pressure multiplier operated by fluid pressure disposed in said frame in sealed communication with the compression chamber inlet for pressurizing said chamber. 